Module appends 

Logic and types for all appends executed by the Coordinator.

Runtime table appends, registrations, and forgets are serialized by the GroupCommitter. FIFO order is required so appends cannot overtake registration or forgetting.

For each command, the committer:

1. allocates a write timestamp from the shared oracle,
2. advances the catalog upper to WriteTimestamp::advance_to,
3. writes the txns shard, retrying InvalidUppers from step 1, and
4. applies the successful write to the oracle.

Step 2 keeps the catalog readable at the oracle read timestamp. It also enforces fencing for a post-fence retry: the fresh oracle timestamp’s advance frontier is above the stale process’s cached catalog upper, so the advance reaches Persist and observes the fence before another txns write.

On environmentd bootstrap in read/write mode, system-table snapshots cannot complete until a txns-shard write has advanced the table uppers. A stale write either linearizes before this barrier and is observed by the snapshot, or conflicts and follows the fenced retry path above. This relies on generations sharing the oracle.

Work that requires coordinator state is returned via Message::GroupCommitApplied.

Structs

BuiltinTableAppend

Helper struct to run a builtin table append.

BuiltinTableAppendCompletion

Completion handle for a builtin-table append response barrier.

DeferredPlan

Describes a plan that is awaiting WriteLocks.

DeferredWrite

GroupCommitNotifier

A handle that allows us to notify the coordinator that a group commit should be run at some point in the future.

GroupCommitPermit

A permit to run a group commit, this must be kept alive for the entire duration of the commit.

GroupCommitRequest 🔒

A group commit staged on the coordinator loop for the GroupCommitter.

GroupCommitWaiter

A handle that returns a future when a group commit needs to be run, and one is not currently being run.

GroupCommitter 🔒

Serializes runtime txns-shard writes off the coordinator loop.

Enums

BuiltinTableUpdateSource 🔒

Describes what action triggered an update to a builtin table.

DeferredOp

An operation that was deferred waiting on a resource to be available.

PendingWriteTxn 🔒

A pending write transaction that will be committing during the next group commit.

TableWriteCmd 🔒

UserWriteResponder 🔒

Where to deliver the result of a PendingWriteTxn::User write.

Statics

REQUIRED_BUILTIN_TABLES 🔒

Tables that we emit updates for when starting a new session.

Functions

notifier

Returns two sides of a “channel” that can be used to notify the coordinator when we want a group commit to be run.

spawn_group_committer 🔒

waiting_on_startup_appends 🔒

When we start a Session we need to update some builtin tables, but we don’t want to wait for these writes to complete for two reasons:

Type Aliases

BuiltinTableAppendNotify

Future that notifies when a builtin table write has completed.